1. Technical Field
The present invention relates to an image printing device and a method of controlling the image printing device.
2. Related Art
Generally, image printing devices having a paper feeding tray that loads a plurality of paper sheets to be overlapped with one another and a print mechanism that performs a printing process for a paper sheet fed and transported from the paper feeding tray one by one have been known. As an image printing device of this type, for example, as disclosed in JP-A- 5-24321, an image printing device that determines paper jam or the degree of duplicate transport by calculating the length of a paper sheet for which a printing process has been completed based on a time when the paper sheet for which the printing process has been completed passes a paper discharge detecting sensor and comparing the result of calculation with data relating to the length of the paper sheet that has been stored in a memory in advance has been proposed. It has been described that the efforts and time to cope with jam and duplicate transport can be reduced and a time for creating a document can be shortened according to the above-described image printing device.
The occurrence of duplicate transport can be generally classified by the type of discrepancy in the overlapping orientation of the printing media. Hereinafter, a duplicate transport with a vertical discrepancy refers to when at least one printing medium is not completely overlapping a first printing medium along the transport direction; a duplicate transport with a horizontal discrepancy refers to when at least one printing medium is not completely overlapping a first printing medium along the main scanning direction. However, although the above-described image printing device can determine whether duplicate transport with a vertical discrepancy (another paper sheet is overlapped and transported with a paper sheet for which a printing process has been completed in a vertically discrepant state) occurs, the image printing device cannot determined whether duplicate transport with a horizontal discrepancy (another paper sheet is overlapped and transported with a paper sheet in a printing process in a horizontally discrepant state) occurs. In addition, there may be a case where a phenomenon of skewed transport in which only one paper sheet in a printing process is transported in a state that the paper sheet is skewed. In such skewed transport, the printing process is needed to be performed again for another paper sheet. However, in a case where the duplicate transport with a horizontal discrepancy occurs, the paper sheet in the printing process can be reused for resuming the printing process. Accordingly, there has been a request for determining the duplicate transport with a horizontal discrepancy, distinguished from the skewed transport.